kevinrich47 wrote: > > But why seem all product in this market using MSVAD ? > I think if they all chose MSVAD,that must be some reason. > I don't think they are all wrong,What do you think? The reasons are likely to be superstition and inertia -- "that's the way we've always done it". The fact that everybody does something in a particular way certainly does not mean that way is right!! Also, those products were produced by companies with experienced driver teams. As I understand it, that does not describe you. Look, you asked for advice, and you've received a lot of it. Now it's up to you to decide what to do with that advice. You can certainly write this as a standalone virtual device starting from MSVAD, or as a WDM filter driver under ks.sys, or as an LFX APO. In my view, the appeal of a system-wide voice changer is extremely limited. The fun part is doing the mathematics to change the voice. If it were me, I would keep everything within my demo application, and write my changer as a DirectShow filter. That way, I could create the demo app and play with the audio mathematics without worrying about blue screens and kernel debugging. After that, you can start thinking about tapping in to the audio driver stack. -- Tim Roberts, timr@xxxxxxxxx Providenza & Boekelheide, Inc.